Foolproof (2003)

Other mistake: Sam asks Leo if she can see his gun, then she points it at him. He laughs and says the clip is removed and that he would never have let her have a loaded gun. She shows him the clip she has stolen from his pocket, loads it into the gun, and cocks it. When she cocks it, a round comes out, meaning that there was already a round in the chamber, so he did give her a loaded gun. She only had one shot, but it was still loaded.

pross79